Today we launch the most comprehensive guide ever to primary education - rating thousands of state-funded schools on their results, teaching, and attendance.

Our unique ranking system uses 21 different government-approved measures, put together from the latest publicly-available data.

We have combined them using a special formula to give each school an overall rating out of 100 – as well as star ratings in the four key categories of Foundation Phase attainment, Key Stage 2 attainment, attendance and staffing and finances.

National league tables tend to only look at Key Stage 2 results – which may mean schools which help all pupils make progress, but only get slightly better than average results overall, are overlooked.

Our ranking system aims to give a far more sophisticated measure of how good schools are – and provide parents with a better idea of which schools will help their child prosper, no matter what their background is.

As a result, our league table tries to factor in other things as well, like whether pupils from disadvantaged backgrounds are making the expected progress – and not just those expected to get top grades.

We have also taken into account factors like what attendance is like, the ratio of teachers to pupils, and the health of the school's finances.

Only schools that offer both infant and junior levels have received an overall school, star rating and ranking, as the majority of schools offer all levels of primary education, but all schools also get an infant and junior ranking based on their performance in these areas so schools that only offer infant or junior provision can be compared to other schools on a similar basis..

Foundation Phase attainment is worth 30 per cent of the total score. This based on how many pupils’ reached the expected outcomes (level 5 in personal and social development, well-being and cultural diversity; language, literacy and communication skills in English or Welsh; and mathematical development) by the end of the Foundation Phase (Year 2) in 2013, and how it compares to 2012.

That measures whether are making good progress during the early years and reaching the standards expected, and if the school is managing to improve year-on-year.

Key Stage 2 attainment is worth 30 per cent of the total. It is based on how many pupils’ reached at least Level 4 in their KS2 assessments in 2013 and how that compares to earlier years. Schools also receive points based on how children on free school meals perform and how attainment by boys and girls compares.

Attendance looks at the percentage of sessions pupils attended and is worth 15 per cent of the total score.

Finally, finances and staffing is worth 25 per cent. This category looks at how big the pupil/teacher ratio is in comparison to the national average.

It is also based on the schools budget per pupil compared to average, and how often in the past five years the school has seen its reserves dip into the red.

Different measures are given weightings based on how important they are likely to be to parents – so the percentage of pupils getting at least a Level 4 in their Key Stage 2 assessments is worth a maximum of 10 points, while the change in that result from 2012 is worth two points.

Scores are worked out by giving the best performing school in each category top marks, with all other schools receiving points adjusted according to their performance in comparison. Schools where performance is below average receive negative points up to a maximum of -0.5%.

Scores for each measure are then added together and adjusted to get a total score out of 100.

Stars are allocated by ranking all the scores in order for each category, then splitting the schools into five groups.

All the data used is the latest available, in most cases from the 2012/13 school year.

Schools are not penalised for not having data. Only schools with below average performance receive negative points. But not having data means they can not score extra points for that measure, potentially putting them behind schools that do not have missing data.

Independent schools are not included in the list as the same data is not available for non-state funded schools.

The ratings are dynamic and will be updated every year, when the new data becomes available from the government.